Excessive vibration over 60mph. Suspension related?

[Aclosefriend]

Hello all. I am new to the forum and just got a great deal on a 2008 HB that is a little dinged, but rust free and perfect under the hood. It has 64k miles and has not had any accidents on the books.

I test drove it for about 20 minutes and did not notice any serious handling issues but it was all on back roads. After purchasing it then taking it on the highway, I noticed over 60mph there is excessive vibration. The headrest on the passenger seat visibly moves back and forth by quite a bit and it feels like it is most pronounced towards the front right wheel. The handling doesn't feel too safe either at high speeds.

The previous owner told me he hit a massive pothot and blew the front right strut. He replaced it ~20k miles ago. Looks like a super budget ebay brand (Auto parts international). He did not replace the front left strut. I've always heard you should replace them in pairs.

I got the wheels aligned, rotated, balanced, and did a full brake job (new rotors, drums, pads, shoes). There has been no difference in the handling at high speeds and the excessive vibration persists. The tires have plenty of tread. The rims are all true with no dents.

Do you think this is a suspension related issue? What else could it be? There is no noise that indicates a bad wheel bearing and the boot on the CV joints look fine. The tires are budget tires but there is no strange wear and plenty of tread left. I wouldn't expect excessive vibration to be caused by suspension though. I've had horribly balanced tires in the pas and this is more what it feels like. When I got this yaris, I ripped the old weights off and had them all rebalanced just to make sure they were all freshly balanced. No change in vibration.

Also, I just noticed that the front right sits about half an inch higher than the front left when measuring from the ground to the fender on the same point.

Any advice would be helpful.